Transmission set for motorboats

ABSTRACT

A transmission set for planing motorboats, comprising a fixing bracket ( 16 ) which at the same time allows to firmly block the containing box linked and engaged to the stern of the hull, in an absolutely invariable position: said bracket ( 16 ) is provided with two longitudinal arms placed in such a way as to support in a fixed point a rotating propeller element in such a way as to receive the hooking of the stern part of the motor or of the inverter connected to the motor, in a constant manner placed in height and in distance, but with the possibility of rotating in a radial direction with respect to the centre of above mentioned elastic support of the stern and therefore of giving the possibility of placing in the position considered the most appropriate said elastic supports of the stern of the engine.

The present invention concerns a transmission set for motorboats comprising a box-shaped body for containing and a for a jointed support onto two axis, perpendicular one to the other, and a box-shaped set for containing and support that may be operatively engaged to the stern part of the hull and passing inside with an o-ring watertight system, and an internal blocking counter-plate that works as a support for the resting of two rotating elastic supports which allow a pre-positioning with a fixed point of the joint of the motion transmission inverter of the engine.

More in detail, the transmission set according to the present invention may be used in a particularly advantageous manner on motorboats of the planing, inboard kind.

As it is already known, in the boats with an inboard motor the transmission of the motion from the motor to one or more propeller placed below the keel, is realized mostly by means of a so-called axis line, i.e. by means of a transmission shaft installed in inclined position with respect to the horizontal direction and connected to the motor and to its motion rotation inverter and to the propeller, by means of a crossing of the lower part of the hull and without any possibility of modification if its inclination, once the initial placing has been performed.

A second typology of motion transmission of an inboard motor is the so-called stern foot, that allows to transfer the outlet power from the motor shaft to a horizontal outlet shaft, placed downwards with respect to the position of the motor shaft, so as to support one or more propellers below the floating line of the boat.

Such a transmission set mainly provides that inside a containing, box-shaped body, a substantially horizontal shaft is housed, besides said outlet shaft, that takes the rotating motion from the motor shaft and transmits it to the outlet shaft by means of an intermediate, mainly vertical shaft, respectively interconnected to the inlet and outlet shafts by means of a first and a second pair of conical cog wheels.

Said solution allows to place the motor near the stern of the board and therefore to considerably reduce the length and the encumbrance of the transmission shaft, in line with said motor.

A third typology, the most up-to-date and presently used one, is the so-called surface transmission which, even if it is applied like the stern foot to the stern of the boat, makes use of only one outlet shaft which, with a rather low inclination, transports the rotating motion of the motor outside of the boat, moving away from the hull until a so-called surface propeller may be applied which is immersed to the centre of its hub.

Above mentioned technologies show the following inconveniences:

-   -   the conventional axis line shows a plurality of inconveniences,         of a functional kind as well as from the point of view of a         global efficiency; the cost of such outline is definitively too         high as it needs, besides the axis line, a waterproofing system         that prevents the sea water from getting inside the boat, a         support near the propeller—as described above—, a steering         system applied behind the propeller for deviating the water flow         coming from said rotating propeller such as to allow to deviate         the boat's direction;     -   the stern foot solution requests conical cog wheels of complex         realization, as they request an absolute precision during         realization as well as during coupling in the installation and         assembling phase. This implies high realization costs.         Furthermore, it should be noted that even disassembling for         maintenance and/or replacing of a conical cog couples         transmission set, implies difficulties for extracting the         gearing, as these are oriented on axis perpendicular one to         another. The following re-assembling requests an extreme care         and precision for avoiding wrong positioning and coupling         tolerances.

It is the aim of the present invention to realize a transmission set of that kind of transmissions making use of surface propellers, for inboard motorboats, which shall mainly respond to above mentioned inconveniences.

At present, document IT 01307592 (Gabriele et al.) is known in which for lowering the considerable costs of the industrial realization of a ball and of its housing, allowing the rotation thereof, the rotation is provided only on two axis: one, vertical to the direction of the boat's motion and one perpendicular to the same.

In consideration of mentioned document, the present invention makes use of a bi-axal solution, i.e. a ring with a circular or polygonal crown with an even number of sides from four on, such as to hook, on the same plane, by means of special and dimensioned pins working on bushes out of suitable material, two movements perpendicular one to another, leaving inside the possibility of making pass a cardan joint that allows, with very small angular movements, the transmission of the motion from a rotating axis solidly engaged with a movable axis. In this way, the present invention allows to considerably reduce the costs and, in the same time it allows, making use of materials of common industrial realization, a wide dimensioning choice and thus the applicable power is linked only to a simple calculation of diameters and torsional resistances and size and typology of the bearings.

The materials used are easily available and therefore may be bought at very low prices.

The connection inside the boat's hull between the transmission and the motor and/or the motion inverter is assured by means of a second cardan joint that therefore allows the independence between the two coupling planes as one is firmly linked to said boat and one oscillates on elastic supports in position and in hooking.

Furthermore, the question of the applicable power has been overcome making use of a system that may not be conditioned by the dimension of the gearing, while the question of the speed and of the easiness of installation has been overcome, according to the present invention, by means of a fixing bracket which at the same time allows to firmly block the containing box linked and engaged to the stern of the hull, in an absolutely invariable position. Said bracket is provided with two longitudinal arms placed in such a way as to support in a fixed point a rotating propeller element. Such shape allows to receive the hooking of the stern part of the motor or of the inverter connected to the motor, in a constant manner, placed in height and in distance, but with the possibility of rotating in a radial direction with respect to the centre of above mentioned elastic support of the stern, and therefore of giving the possibility of placing in the position considered the most appropriate said elastic supports of the stern of the engine, whereby the installer must not inquire about the distance and/or the height of the motor-transmission coupling. From all above, it results how easy said installation may be and how cheap.

The present invention will be described more in detail hereinbelow relating to the enclosed drawings, in which:

FIGS. 1, 2 and 3 show the counter-plate of the inner transmission set and the details for fixing the support on astern;

FIG. 4 shows a lateral scheme of the installation of the transmission set.

The enclosed figures show a transmission set for motorboats according to the present invention, comprising:

-   -   a propeller 1,     -   a propeller supporting rod 2,     -   a first box-shaped body 3 that may be oriented in horizontal and         in vertical direction,     -   a directional skeg 4,     -   a ring 5 that allows the orientation on two axis of the         orienting box-shaped body,     -   a second box-shaped body 6 firmly fixed to the boat's stern,     -   a back cardan joint 7,     -   a front cardan joint 9,     -   an axis 8 for the connection and the support between the back         and front cardan joint,     -   an inverter 10 for the transmission rotation,     -   a supporting plate 11, self-centering, for fixing the supports         astern,     -   an elastic element 14 of the supports astern,     -   half-shells 12 for blocking the elastic element,     -   a pin 15 for hooking the two half-shells in a predetermined         point,     -   a bracket 16 for hooking to the inverter,     -   a central pin 13 for the joint between the elastic element and         the bracket,     -   a motor 17,     -   a front elastic support 18. 

1. A transmission set for planing motorboats, comprising: a first box-shaped body (3) for containing and supporting a propeller supporting rod (2), whereby said rod may be oriented according to two axis at 90° one to another, one parallel and the other perpendicular to the longitudinal axis of the hull, a second box-shaped body (6), engaged to the hull of a boat, for containing and supporting an intermediate joining rod (8), a system (5) for joining the two box-shaped bodies (3, 6), out of high resistance metal and with a great thickness, having the shape of a circular or polygonal crown with sides in even number from four on, and that allows, inside the same, the passage of a cardan joint that rotatingly engages the propeller carrying rod (2) inserted in the orienting box-shaped body (3) with the rod (8) supported and inserted in the box-shaped body (6) fixed to the hull, that allows the orientation of said box-shaped body (3) in the two above mentioned directions by means of four pins of such materials and dimensions as to support the provided stresses, rotating in bushes out of sea-bronze and/or other stainless and anti-friction material, and characterized in a fixing system consisting of a outer plate with a great thickness out of stainless material, hooked to an inner counter-plate (11) supporting two arms onto which, at a determined point, half-shells (12) for containing elastic elements (14) with circular shape are placed, with the front part that may be riveted for blocking the elastic element once it has been placed, and that form the rotation fulcrum of the motor and make it orienting like an arch according to the needs of the installer.
 2. A transmission group according to claim 1, characterized in the presence of a (right and left) plate (16) that gets fixed to the back part of the motor and/or of the inverter, with a circular pin (13) that gets fixed and inserted in the central part of the round-shaped elastic element (14) so as to provide a connection point between the counter-plate fixed to the transmission and the motor and/or the inverter.
 3. A transmission group according to claim 1, characterized in a fixing bracket which, at the same time, allows to firmly block the containing box firmly engaged with the stern of the boat, in an absolutely invariable position; whereby said bracket has two longitudinal arms placed in such a way as to support, in a determined point, a rotating elastic element so as to receive the hooking of the stern part of the motor or of the inverter connected to the motor, in a manner constantly placed in distance and in height but having the possibility of rotating in radial direction to the centre of the elastic supports of the mentioned side astern, and therefore giving the possibility of placing said elastic supports in the most appropriate position in the stern part of the motor.
 4. A transmission set according to claim 1, comprising: a propeller (1), a propeller supporting rod (2), a first box-shaped body (3) that may be oriented in horizontal and in vertical direction, a directional skeg (4), a ring (5) that allows the orientation on two axis of the orienting box-shaped body, a second box-shaped body (6) firmly fixed to the boat's stern, a back cardan joint (7), a front cardan joint (9), an axis (8) for the connection and the support between the back and front cardan joint, an inverter (10) for the transmission rotation, characterized in the presence of: a supporting plate (11), self-centering, for fixing the supports astern, an elastic element (14) of the supports astern, half-shells (12) for blocking the elastic element, a pin (15) for hooking the two half-shells in a predetermined point, a bracket (16) for hooking to the inverter, a central pin (13) for the joint between the elastic element and the bracket, a motor (17), a front elastic support (18). 